The present invention relates to a personal ornament having a white coating layer, and a process for producing the same. More particularly, the present invention relates to a low-priced personal ornament having an inexpensive white-colored stainless steel coating layer excellent in long-term corrosion resistance on the surface of a base article made of a less corrosive metal or alloy thereof; and a process for producing the personal ornament.
Heretofore, many personal ornaments such as watches, necklaces, pendants, and brooches are made from a copper alloy owing to workability, material cost, and other reasons.
However, a personal ornament made from a copper alloy, which is less corrosion-resistant, as the base material is usually covered with a plating layer formed by wet plating to protect the base material from corrosion. This plating layer is usually constituted of an underlying nickel plating layer formed by wet plating and an outermost plating layer formed thereon by wet plating. For making the outermost layer golden in color, a gold plating layer is formed on the nickel layer by wet plating. For making the outermost layer white in color tone, a palladium plating layer, a palladium alloy plating layer, or a rhodium plating layer is formed on the nickel layer by wet plating. The plating layer is generally formed in a thickness ranging from 1 to 5 xcexcm.
The aforementioned personal ornaments, however, have disadvantage of high cost owing to the noble metal-containing outermost plating layer for corrosion resistance. Therefore, low-priced personal ornaments naturally have a thin outermost plating layer, lacking in long-term corrosion resistance. Moreover, in the production of the low-priced ornaments, the noble metal plating bath should be strictly controlled and maintained in order to obtain stably a thin outermost plating layer, and the workers for the plating operation should have high skill in order to obtain stably the outermost plating layer of the desired color tone. Furthermore, a personal ornament having a characteristic white color of the stainless steel has not yet been produced at a low price.
Accordingly, there are demanded a low-priced personal ornament having an inexpensive white-colored stainless steel coating layer excellent in long-term corrosion resistance on the surface of a base article made of a less corrosive metal or alloy thereof; and a process for producing the personal ornament.
The present invention has been made to solve the problems of the aforementioned prior art techniques, and an object of the present invention is to provide a low-priced personal ornament having an inexpensive white-colored stainless steel coating layer excellent in long-term corrosion resistance on the surface of a base article made of a less corrosive metal or alloy thereof; and a process for producing the personal ornament.
The first personal ornament having a white coating layer of the present invention comprises
a base article of the personal ornament made of a metal, and
a white-colored stainless steel coating layer formed by a dry plating process on at least a part of the surface of the base article.
The above base article of the personal ornament is made usually of tungsten carbide or tantalum carbide.
The second personal ornament having a white coating layer of the present invention comprises:
a base article of the personal ornament made of a nonferrous metal,
an underlying plating layer formed on the surface of the base article, and
a white-colored stainless steel coating layer formed by a dry plating process on at least a part of the surface of the underlying plating layer.
The base article of the personal ornament of the second embodiment is made usually of at least one nonferrous metal selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, zinc, zinc alloys, magnesium, and magnesium alloys.
The first or second personal ornament having a white coating layer of the present invention may have, on the surface of the stainless steel coating layer, a white-colored noble metal coating layer in a thickness ranging from 0.04 to 0.3 xcexcm formed by a dry plating process.
The underlying plating layer may have a multilayer structure constituted of at least one plating layer formed by a wet plating process, and at least one different plating layer formed by a dry plating process.
The underlying plating layer is preferably a coating layer formed by a wet plating process and composed of at least one metal selected from the group consisting of gold, copper, nickel, chromium, tin, palladium, nickel-phosphorus alloys, nickel alloys excluding nickel-phosphorus alloys, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
The nickel-phosphorus alloy plating layer as the underlying plating layer is preferably a hard coating layer having been treated for age hardening.
For prevention of development of nickel allergy, the underlying plating layer preferably contains no nickel. Such an underlying plating layer is composed preferably of at least one nickel-free metal selected from the group consisting of gold, copper, chromium, tin, palladium, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys, and is formed by a wet plating process.
The underlying plating layer is preferably a coating layer formed by a dry plating process and is composed of titanium carbide, zirconium carbide, or tantalum carbide.
The entire thickness of the underlying plating layer is usually in the range of from 0.2 to 30 xcexcm.
In the first and second personal ornament having a white coating layer of the present invention, the white-colored stainless steel coating layer is composed preferably of an austenitic stainless steel, particularly an austenitic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 8-22 vol % of nickel, and 15-26 vol % of chromium.
For prevention of development of nickel allergy, the white-colored stainless steel layer preferably contains no nickel. Such a white-colored stainless steel coating layer is composed preferably of a nickel-free ferritic stainless steel, particularly nickel-free ferritic stainless steels having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 14-20 vol % of chromium, and 0.4-2.5 vol % of molybdenum.
The above white-colored stainless steel coating layer can be formed by a dry plating process selected from a sputtering method, an arc evaporation method or an ion-plating method.
In the first or second personal ornament having a white coating layer of the present invention, on the surface of the base article or of the underlying plating layer, at least one plating layer different in color tone from the white-colored stainless steel coating layer may be formed by a dry plating process in addition to the stainless steel coating layer formed by a dry plating process.
The plating layer different from the stainless steel coating layer is preferably a coating layer composed of gold, a gold alloy, titanium nitride, or zirconium nitride.
The first process for producing a personal ornament having a white coating layer of the present invention comprises the steps of:
forming a base article of the personal ornament from a metal (or an alloy) by machining,
washing and degreasing the surface of the base article,
setting the base article in a dry plating apparatus selected from sputtering systems (apparatuses), arc evaporation systems (apparatuses), and ion-plating systems (apparatuses), and cleaning the base article by bombard cleaning in an argon gas atmosphere, and
forming a white-colored stainless steel coating layer on the base article by a dry plating process.
The metal employed for forming the base article of the above personal ornament is usually tungsten carbide or tantalum carbide.
The second process for producing a personal ornament having a white coating layer of the present invention comprises the steps of:
forming a base article of the personal ornament from a nonferrous metal (or an alloy) by machining;
washing and degreasing the surface of the base article;
forming on the surface of the base article an underlying plating layer by a wet plating process or a dry plating process;
setting the base article having the underlying plating layer in a dry plating apparatus selected from sputtering systems, arc evaporation systems, and ion-plating systems, and cleaning the surface of the underlying plating layer by bombard cleaning in an argon gas atmosphere; and
forming a white-colored stainless steel coating layer by a dry plating process on the surface of the underlying plating layer.
The nonferrous metal employed for forming the base article of the above personal ornament is at least one nonferrous metal selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, zinc, zinc alloys, magnesium, and magnesium alloys.
In the first or second process for producing a personal ornament having a white coating layer of the present invention, the process may further comprise, after the step of forming the white-colored stainless steel coating layer, a step of forming a white-colored noble metal coating layer in a thickness ranging from 0.04 to 0.3 xcexcm on the surface of the stainless steel coating layer by a dry plating process.
The underlying plating layer may have a multilayer structure constituted of at least one plating layer formed by a wet plating process on the surface of the base article, and at least one plating layer formed thereon by a dry plating process.
The underlying plating layer is preferably formed by a wet plating process from at least one metal selected from the group consisting of gold, copper, nickel, chromium, tin, palladium, nickel-phosphorus alloys, nickel alloys excluding nickel-phosphorus alloys, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
In the case where a nickel-phosphorus alloy is employed as the underlying plating layer, the nickel-phosphorus alloy plating layer is preferably treated for age hardening at 200 to 450xc2x0 C. for 20 to 60 minutes to harden the nickel-phosphorus alloy plating layer.
For prevention of development of nickel allergy, the underlying plating layer is preferably formed by a wet plating process from at least one nickel-free metal selected from the group consisting of gold, copper, chromium, tin, palladium, copper-tin-palladium alloys, copper alloys excluding copper-tin-palladium alloys, tin alloys excluding copper-tin-palladium alloys, and palladium alloys excluding copper-tin-palladium alloys.
The underlying plating layer is preferably formed from titanium carbide, zirconium carbide, or tantalum carbide by a dry plating process.
The entire thickness of the underlying plating layer is usually in the range of 0.2 to 30 xcexcm.
In the first and second process of forming a personal ornament having a white coating layer of the present invention, the white-colored stainless steel coating layer is preferably an austenitic stainless steel, particularly an austenitic stainless steel having a composition of 0.01-0.12 vol % of carbon, 0.1-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 8-22 vol % of nickel, and 15-26 vol % of chromium, and is formed by a sputtering method, an arc evaporation method, or an ion plating method.
For prevention of nickel allergy, the white-colored stainless steel preferably contains no nickel. Such a white-colored stainless steel coating layer is composed preferably of a ferritic stainless steel not containing nickel, particular a ferritic stainless steel not containing nickel having a composition of 0.01-0.12 vol % of carbon, 0.10-1.0 vol % of silicon, 1.0-2.5 vol % of manganese, 14-20 vol % of chromium and 0.4-2.5 vol % of molybdenum, and is formed by a sputtering method, an arc evaporation method or an ion plating method.
The first or second process for producing a personal ornament having a white coating layer of the present invention further comprises, after the steps of forming a white-colored stainless steel coating layer on the surface of the ornament base article or of the underlying coating layer, at least once the steps of masking a part of the stainless steel coating layer, forming a plating layer different in color tone from the stainless steel coating layer on the surface of the stainless steel coating layer and the surface of the mask by a dry plating process, and removing the mask and the coating layer on the mask, to thereby provide an outermost plating layer (finish-plating layer) having a white-colored stainless steel coating layer portion and at least one plating layer portion different in color tone from the stainless steel coating layer.
The plating layer different in color tone from the stainless steel coating layer is preferably obtained by forming at least one coating layer from a metal selected from the group consisting of gold, gold alloys, titanium nitride, hafnium nitride, and zirconium nitride by a dry plating process selected from sputtering methods, arc evaporation methods, and ion plating methods.